Toilet tank



FIG. 1 is a perspective view of an embodiment of the claimed design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines formed by equal length dashes in the drawings illustrate unclaimed portions of the design. The broken lines formed by unequal length dashes illustrate unclaimed boundaries of claimed surfaces. 

CLAIM I claim the ornamental design for a toilet tank, as shown and described. 